Distributed Linear Precoding and User Selection in Coordinated Multicell Systems

In this manuscript we tackle the problem of semidistributed user selection with distributed linear precoding for sum rate maximization in multiuser multicell systems. A set of adjacent base stations (BS) form a cluster in order to perform coordinated transmission to cell-edge users, and coordination is carried out through a central processing unit (CU). However, the message exchange between BSs and the CU is limited to scheduling control signaling and no user data or channel state information (CSI) exchange is allowed. In the considered multicell coordinated approach, each BS has its own set of cell-edge users and transmits only to one intended user while interference to non-intended users at other BSs is suppressed by signal steering (precoding). We use two distributed linear precoding schemes, Distributed Zero Forcing (DZF) and Distributed Virtual Signalto-Interference-plus-Noise Ratio (DVSINR). Considering multiple users per cell and the backhaul limitations, the BSs rely on local CSI to solve the user selection problem. First we investigate how the signal-to-noise-ratio (SNR) regime and the number of antennas at the BSs impact the effective channel gain (the magnitude of the channels after precoding) and its relationship with multiuser diversity. Considering that user selection must be based on the type of implemented precoding, we develop metrics of compatibility (estimations of the effective channel gains) that can be computed from local CSI at each BS and reported to the CU for scheduling decisions. Based on such metrics, we design user selection algorithms that can find a set of users that potentially maximizes the sum rate. Numerical results show the effectiveness of the proposed metrics and algorithms for different configurations of users and antennas at the base stations.

Nostalgia Studio. A game engine for creating collaborative multiplayer online graphic adventure games

No decorrer do projeto SELEAG foi desenvolvido um jogo de aventura gráfica educativo com o propósito de ensinar história, cultura e relações sociais aos alunos. Este jogo foi avaliado em contexto de sala de aula em diversos países, obtendo resultados positivos. No entanto, por motivos técnicos, alguns dos objetivos propostos pelo projeto não puderam ser devidamente explorados, como permitir que o jogo fosse extensível por outros educadores ou suportar a colaboração online entre os jogadores. Nomeadamente, as ferramentas utilizadas para desenvolver o jogo eram demasiado complicadas para serem utilizadas fora da equipa de desenvolvimento, o que limitou a extensibilidade do projeto, e tornou impossível que educadores sem conhecimentos de programação fossem também capazes de traduzir os seus conteúdos educativos para este formato. Além disso, apesar do jogo possuir algumas funcionalidades de colaboração online, toda a interação era efetuada externamente ao jogo, através de um fórum de mensagens, o que demonstrou ser pouco motivante para os jogadores, pois muitos deles nem se aperceberam que havia uma componente de colaboração no jogo. O objetivo desta tese incide sobre estes dois problemas, e consistiu em desenvolver um editor e motor de jogo com uma interface simples de utilizar, que não necessita de conhecimentos prévios de programação, e que permite criar jogos de aventura gráfica com uma componente de colaboração online verdadeiramente embebida na jogabilidade. A aplicação desenvolvida foi testada por um conjunto de utilizadores de diversas áreas, tendo-se obtido resultados que demonstram a acessibilidade e simplicidade da mesma, independentemente do nível de experiência prévio de programação do utilizador. A componente de colaboração online foi também muito bem recebida pelos utilizadores, os quais demonstraram bastante interesse em ver jogos de aventura gráfica com componente de colaboração online serem desenvolvidos no futuro.

Short- and medium-term effects of manual therapy on cervical active range of motion and pressure pain sensitivity in latent myofascial pain of the upper trapezius muscle: a randomized controlled trial

Objective: The purpose of this study was to investigate effects of different manual techniques on cervical ranges of 17 motion and pressure pain sensitivity in subjects with latent trigger point of the upper trapezius muscle. 18 Methods: One hundred seventeen volunteers, with a unilateral latent trigger point on upper trapezius due to computer 19 work, were randomly divided into 5 groups: ischemic compression (IC) group (n = 24); passive stretching group (n = 20 23); muscle energy technique group (n = 23); and 2 control groups, wait-and-see group (n = 25) and placebo group 21 (n = 22). Cervical spine range of movement was measured using a cervical range of motion instrument as well as 22 pressure pain sensitivity by means of an algometer and a visual analog scale. Outcomes were assessed pretreatment, 23 immediately, and 24 hours after the intervention and 1 week later by a blind researcher. A 4 × 5 mixed repeated- 24 measures analysis of variance was used to examine the effects of the intervention and Cohen d coefficient was used. 25 Results: A group-by-time interaction was detected in all variables (P b .01), except contralateral rotation. The 26 immediate effect sizes of the contralateral flexion, ipsilateral rotation, and pressure pain threshold were large for 3 27 experimental groups. Nevertheless, after 24 hours and 1 week, only IC group maintained the effect size. 28 Conclusions: Manual techniques on upper trapezius with latent trigger point seemed to improve the cervical range of 29 motion and the pressure pain sensitivity. These effects persist after 1 week in the IC group. (J Manipulative Physiol 301 Ther 2013;xx:1-10)

Optimal controllers with complex order derivatives

This paper studies the optimization of complex-order algorithms for the discrete-time control of linear and nonlinear systems. The fundamentals of fractional systems and genetic algorithms are introduced. Based on these concepts, complexorder control schemes and their implementation are evaluated in the perspective of evolutionary optimization. The results demonstrate not only that complex-order derivatives constitute a valuable alternative for deriving control algorithms, but also the feasibility of the adopted optimization strategy.

A multi-objective approach for the motion planning of redundant manipulators

Kinematic redundancy occurs when a manipulator possesses more degrees of freedom than those required to execute a given task. Several kinematic techniques for redundant manipulators control the gripper through the pseudo-inverse of the Jacobian, but lead to a kind of chaotic inner motion with unpredictable arm configurations. Such algorithms are not easy to adapt to optimization schemes and, moreover, often there are multiple optimization objectives that can conflict between them. Unlike single optimization, where one attempts to find the best solution, in multi-objective optimization there is no single solution that is optimum with respect to all indices. Therefore, trajectory planning of redundant robots remains an important area of research and more efficient optimization algorithms are needed. This paper presents a new technique to solve the inverse kinematics of redundant manipulators, using a multi-objective genetic algorithm. This scheme combines the closed-loop pseudo-inverse method with a multi-objective genetic algorithm to control the joint positions. Simulations for manipulators with three or four rotational joints, considering the optimization of two objectives in a workspace without and with obstacles are developed. The results reveal that it is possible to choose several solutions from the Pareto optimal front according to the importance of each individual objective.

Analysis of financial data series using fractional Fourier transform and multidimensional scaling

The goal of this study is the analysis of the dynamical properties of financial data series from worldwide stock market indexes during the period 2000–2009. We analyze, under a regional criterium, ten main indexes at a daily time horizon. The methods and algorithms that have been explored for the description of dynamical phenomena become an effective background in the analysis of economical data. We start by applying the classical concepts of signal analysis, fractional Fourier transform, and methods of fractional calculus. In a second phase we adopt the multidimensional scaling approach. Stock market indexes are examples of complex interacting systems for which a huge amount of data exists. Therefore, these indexes, viewed from a different perspectives, lead to new classification patterns.

Dynamics of the Dow Jones and the NASDAQ stock indexes

The goal of this study is the analysis of the dynamical properties of financial data series from worldwide stock market indices. We analyze the Dow Jones Industrial Average ( ∧ DJI) and the NASDAQ Composite ( ∧ IXIC) indexes at a daily time horizon. The methods and algorithms that have been explored for description of physical phenomena become an effective background, and even inspiration, for very productive methods used in the analysis of economical data. We start by applying the classical concepts of signal analysis, Fourier transform, and methods of fractional calculus. In a second phase we adopt a pseudo phase plane approach.

Fractional Dynamics and Control of Distributed Parameter Systems

Fractional Calculus (FC) goes back to the beginning of the theory of differential calculus. Nevertheless, the application of FC just emerged in the last two decades, due to the progress in the area of chaos that revealed subtle relationships with the FC concepts. In the field of dynamical systems theory some work has been carried out but the proposed models and algorithms are still in a preliminary stage of establishment. Having these ideas in mind, the paper discusses a FC perspective in the study of the dynamics and control of some distributed parameter systems.

Picture marks semiotics between ontwerpen and vormgeving

This project seeks to implement and operationalize an analytical and schematic tool proposed in the doctoral thesis of Eduardo Aires applied to the first pages of newspapers (FBAUP: 2006), to the study of the symbol within the visual identity – the picture mark – starting with its semiotic analysis. Our research has the main objective to contribute to providing guidelines to facilitate both the communication and the methodology used by students and professionals of graphic design, translating, in a graphic way, implicit phenomena that is still in the spectrum of intuition, concerning Identity Design (specifically, the design of the graphic mark), and bringing them to the field of scientific definitions. It is our intention to provide the design of a picture mark, a graphic sign which is intended to synthesize, identify and bring positive values about an entity, with an educational tool that would constitute itself as knowledge so far nonexistent.

Semantic social network analysis

Mestrado em Engenharia Informática

Efeitos imediatos da mobilização com movimento na dor, Amplitude de movimento e actividade electromiográfica dos músculos da cintura escapular em indivíduos com síndrome do conflito subacromial

Introdução: A síndrome do conflito subacromial (SCSA) é a causa mais frequente de dor no ombro. Alterações na cinemática escapuloumeral e na activação dos músculos escapulares têm sido identificadas em pessoas com SCSA. A mobilização com movimento (MWM) é uma técnica de terapia manual, desenvolvida por Mulligan, que visa normalizar a cinemática articular. Objectivos: Determinar os efeitos imediatos da MWM na dor, na amplitude de movimento (ADM) de abdução no plano da escápula (APE), e na amplitude do sinal electromiográfico (EMG) do trapézio e grande dentado (GD), em pessoas com SCSA. Métodos: Foram incluídas no estudo 24 pessoas com SCSA, divididas de forma aleatória em 2 grupos de 12, MWM e Placebo. As medidas de resultados avaliadas foram: a dor nos testes de Neer e Hawkins-Kennedy; o limiar de dor à pressão; a ADM de APE até ao início da dor; e a percentagem da contracção isométrica voluntária máxima dos músculos trapézio (superior, médio e inferior) e GD. Resultados: A aplicação da MWM resultou numa significativa diferença, com redução da dor, no teste de Hawkins-Kennedy (p=0,028), num aumento do limiar de dor à pressão (p=0,002) e da ADM de APE até ao início da dor (p=0,010), e numa diminuição da actividade EMG do trapézio superior (TS), na fase concêntrica, abaixo dos 90˚ (p=0,028), comparativamente ao grupo Placebo. Foi, ainda, identificada uma diminuição estatisticamente significativa da actividade EMG do TS, nas restantes fases do movimento (p<0,05), um aumento do limiar de dor à pressão (p<0,001) e da ADM até ao início da dor (p=0,006) entre, antes e após a intervenção com MWM. Conclusão: A MWM poderá ser uma técnica efectiva em indivíduos com SCSA, pelos seus efeitos na redução de dor, aumento de ADM até ao início da dor e diminuição da actividade EMG do TS.

Framework de controlo de acessos para Triple-stores com interface Sail API

Grande parte dos triples-stores são open source e desenvolvidos em Java, disponibilizando interfaces standards e privadas de acesso. A grande maioria destes sistemas não dispõe de mecanismos de controlo de acessos nativos, o que dificulta ou impossibilita a sua adopção em ambientes em que a segurança dos factos é importante (e.g. ambiente empresarial). Complementarmente observa-se que o modelo de controlo de acesso a triplos e em particular a triplos descritos por ontologias não está standardizado nem sequer estabilizado, havendo diversos modelos de descrição e algoritmos de avaliação de permissões de acesso. O trabalho desenvolvido nesta tese/dissertação propõe um modelo e interface de controlo de acesso que permite e facilite a sua adopção por diferentes triple-stores já existentes e a integração dos triples-stores com outros sistemas já existentes na organização. Complementarmente, a plataforma de controlo de acesso não impõe qualquer modelo ou algoritmo de avaliação de permissões, mas pelo contrário permite a adopção de modelos e algoritmos distintos em função das necessidades ou desejos. Finalmente demonstra-se a aplicabilidade e validade do modelo e interface propostos, através da sua implementação e adopção ao triple-store SwiftOWLIM já existente, que não dispõe de mecanismo de controlo de acessos nativo.

Extracção de regras de associação com itens raros e frequentes

Ao longo dos últimos anos, as regras de associação têm assumido um papel relevante na extracção de informação e de conhecimento em base de dados e vêm com isso auxiliar o processo de tomada de decisão. A maioria dos trabalhos de investigação desenvolvidos sobre regras de associação têm por base o modelo de suporte e confiança. Este modelo permite obter regras de associação que envolvem particularmente conjuntos de itens frequentes. Contudo, nos últimos anos, tem-se explorado conjuntos de itens que surgem com menor frequência, designados de regras de associação raras ou infrequentes. Muitas das regras com base nestes itens têm particular interesse para o utilizador. Actualmente a investigação sobre regras de associação procuram incidir na geração do maior número possível de regras com interesse aglomerando itens raros e frequentes. Assim, este estudo foca, inicialmente, uma pesquisa sobre os principais algoritmos de data mining que abordam as regras de associação. A finalidade deste trabalho é examinar as técnicas e algoritmos de extracção de regras de associação já existentes, verificar as principais vantagens e desvantagens dos algoritmos na extracção de regras de associação e, por fim, desenvolver um algoritmo cujo objectivo é gerar regras de associação que envolvem itens raros e frequentes.

EMMON - EMbedded MONitoring

Despite the steady increase in experimental deployments, most of research work on WSNs has focused only on communication protocols and algorithms, with a clear lack of effective, feasible and usable system architectures, integrated in a modular platform able to address both functional and non–functional requirements. In this paper, we outline EMMON [1], a full WSN-based system architecture for large–scale, dense and real–time embedded monitoring [3] applications. EMMON provides a hierarchical communication architecture together with integrated middleware and command and control software. Then, EM-Set, the EMMON engineering toolset will be presented. EM-Set includes a network deployment planning, worst–case analysis and dimensioning, protocol simulation and automatic remote programming and hardware testing tools. This toolset was crucial for the development of EMMON which was designed to use standard commercially available technologies, while maintaining as much flexibility as possible to meet specific applications requirements. Finally, the EMMON architecture has been validated through extensive simulation and experimental evaluation, including a 300+ nodes testbed.

Direct search optimization application programming interface with remote access

Search Optimization methods are needed to solve optimization problems where the objective function and/or constraints functions might be non differentiable, non convex or might not be possible to determine its analytical expressions either due to its complexity or its cost (monetary, computational, time,...). Many optimization problems in engineering and other fields have these characteristics, because functions values can result from experimental or simulation processes, can be modelled by functions with complex expressions or by noise functions and it is impossible or very difficult to calculate their derivatives. Direct Search Optimization methods only use function values and do not need any derivatives or approximations of them. In this work we present a Java API that including several methods and algorithms, that do not use derivatives, to solve constrained and unconstrained optimization problems. Traditional API access, by installing it on the developer and/or user computer, and remote API access to it, using Web Services, are also presented. Remote access to the API has the advantage of always allow the access to the latest version of the API. For users that simply want to have a tool to solve Nonlinear Optimization Problems and do not want to integrate these methods in applications, also two applications were developed. One is a standalone Java application and the other a Web-based application, both using the developed API.